We can observe that CPU 6 and 7 are less busy servicing interrupts then the other but are still used for eth2 and eth3. Let’s say we want the NDB threads to run on these 2 CPUs and get rid of the interrupts. The Linux kernel allows to mask CPUs to interrupts. Considering the output above, eth2 is on IRQ 154 and eth3 is on IRQ 170. A bitmask of 6 “1”s equals 1 + 2 + 4 +8 + 16 + 32 = 63 so